"but I can imagine quite a few where it will be"
Such as? I can see it being useful for the 1st guy thru the door but otherswise?
Tank driver -- most drive with their head popped out of the tank. An M1 and it's crew was lost in Bagdad when it's driver was shot dead -- the tank drove off of a bridge an the other crew members died.
Guard duty -- protection against snipers. Right now body armour does great -- except for the face.
Who else knows.. I wonder how many of our soldiers have died form bullets to the face...